冲刺阶段个人博客03

　　昨天我们小组进行了任务的进一步划分，我要完成客户端和浏览器之间的数据传输部分，而这和前台的接口需要我和同伴协商后完成。昨天我练习了是用多线程断点下载技术，作为我们的客户端和服务器之间的数据连接工具。在电脑上运行我写的程序是没有问题了，但是移植到android系统上就会错误，目前还没有找到问题所在，系统提示说是权限被拒绝，但是我明明在清单文件中加了相应的权限的啊。今天我需要找到这个问题，并解决它。昨天写的程序还是有一些缺陷，比如说下载过程中不能得到文件下载的进度，所以今天我还要改进这个程序。

我的程序代码：

  1　　　public static int threadCount = 3;
    public static long blockSize;
    public static int runingThreadCount;
    private static int status;
    
    /**
     * @param res        资源路径
     * @param file        下载后的文件存放位置(路径名+加文件名)
     * @return            下载是否成功
     */
    public static int download(String res,String file){
        
        final String path = res,filename =  file;
        new Thread(){
            public void run() {
                int length = 0;
                HttpURLConnection con = null;
                try {
                    //设置连接相关的参数
                    con = (HttpURLConnection) new URL(path).openConnection();
                    con.setRequestMethod("GET");
                    con.setConnectTimeout(10000);
                    con.setReadTimeout(5000);
                    con.connect();
                    
                    if (con.getResponseCode()==200) {
                        System.out.println("DownloadUtils new Thread HttpURLConnection 连接成功！");
                        //得到服务器文件的大小
                        length = con.getContentLength();
                        //建立一个空白文件
                        File f = new File(filename);
                        RandomAccessFile raf = new RandomAccessFile(f, "rw");
                        //设置文件的大小
                        raf.setLength(length);
                        raf.close();
                        //计算每个线程应当下载的文件的大小
                        blockSize = length / threadCount;
                        //开启子线程下载文件
                        runingThreadCount = threadCount;
                        for (int i = 0; i < threadCount; i++) {
                            long startIndex = i * blockSize;
                            long endIndex = (i + 1) * blockSize - 1;
                            if (i == threadCount - 1)
                                endIndex = length;
                            System.out.println("开启子线程 "+(i+1)+" 下载位置 "+startIndex+" - "+endIndex);
                            new DownloadThread((i+1),path, startIndex, endIndex, f).start();
                        } 
                    }else{
                        System.out.println("DownloadUtils new Thread HttpURLConnection 连接失败！");
                    }
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } finally {
                    if(con != null)
                        con.disconnect();
                }

            };
        }.start();
        
        return status;
    }
    
    private static class DownloadThread extends Thread{
        private int threadId;
        private long startIndex,endIndex;    //下载开始点和结束点
        private String path;                //下载路径
        private File file;                    //文件存放路径和文件名
        public DownloadThread(int id,String path,long startIndex,long endIndex,File file){
            this.startIndex = startIndex;
            this.endIndex = endIndex;
            this.path = path;
            this.file = file;
            threadId = id;
        }
        
        @Override
        public void run() {
            // TODO Auto-generated method stub
            super.run();
            HttpURLConnection con = null;
            
            // 从文件中读出上次下载的位置，此次应当接着上次的位置开始下载
            long tatol = 0;
            try{
                BufferedReader read = new BufferedReader(new FileReader(threadId+".txt"));
                String s = null;
                while((s = read.readLine())!=null){
                    tatol = Long.parseLong(s);
                }
                System.out.println("子线程"+threadId+"上次下载文件总大小："+tatol);
                startIndex += tatol;
                System.out.println("子线程"+threadId+"本次下载位置："+startIndex+" - "+endIndex);
                read.close();
            }catch(Exception e){}
            try {
                //设置连接的参数
                con = (HttpURLConnection) new URL(path).openConnection();
                con.setRequestMethod("GET");
                con.setConnectTimeout(10000);
                //设置请求头，这个请求头必须设置
                con.setRequestProperty("Range", "bytes="+startIndex+"-"+endIndex);
                
                //得到服务器的响应码
                int code = con.getResponseCode();
                if(code / 100 == 2){
                    System.out.println("线程"+threadId+"连接成功，下载开始！"+"响应码："+code);
                    //建立自由读写文件流
                    RandomAccessFile raf = new RandomAccessFile(file,"rw");
                    
                    
                    //将读写指针移动到本线程下载资源的首位置
                    raf.seek(startIndex);
                    InputStream is = con.getInputStream();
                    PrintStream out = new PrintStream(new FileOutputStream(threadId+".txt",true));
                    int len = 0;
                    byte[] buffer = new byte[1024*1024];
                    //开始读写
                    System.out.println("子线程"+threadId+"读写文件开始！");
                    while((len = is.read(buffer))!=-1){
                        raf.write(buffer,0,len);
                        tatol += len;
                        out.println(tatol);
                    }
                    out.close();
                    is.close();
                    raf.close();
                    System.out.println("线程"+threadId+"下载成功！");
                }else{
                    System.out.println("线程"+threadId+"连接失败！"+"响应码："+code);
                }
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                System.out.println("线程"+threadId+"下载异常！");
            }finally{
                if(con!=null)
                    con.disconnect();
                synchronized (DownloadUtils.class) {
                    runingThreadCount--;
                    if (runingThreadCount < 1) {
                        System.out.println("所有线程都下载完毕，删除临时记录文件！");
                        for (int i = 1; i <= threadCount; i++) {
                            File f = new File(i + ".txt");
                            System.out.println("临时记录文件文件 ‘" + i + ".txt’删除 " + f.delete());
                        }
                    }
                }
            }
        }
    }